Ricoh B234 Service Manual page 766

COPY PROCESS
DRUM POTENTIAL MEASUREMENT
The drum potential sensor [5] detects the electric potential on the drum to correct
various process control elements.
DEVELOPMENT
The development rollers [6] turn and carry the developer to the drum. When the
magnetic developer brush on the development rollers contacts the drum surface,
the high negative charge of the white areas in the latent image force the toner with
its low negative charge into the black areas. This forced migration of toner over the
latent image forms the copy image on the drum.
PRE-TRANSFER
Light from the pre-transfer lamp [7] reduces the amount of charge on the drum
surface to improve the ease of image transfer.
IMAGE TRANSFER
Paper is fed to the area between the drum surface and the transfer belt [8] at the
proper time to align the copy paper and the developed image on the drum. Then,
the transfer bias roller and brush apply a high positive charge to the reverse side of
the paper through the transfer belt. This positive charge pulls the toner particles
from the drum to the paper. At the same time, the paper is electrically attracted to
the transfer belt.
PAPER SEPARATION
Paper separates from the drum as a result of the electrical attraction between the
paper and the transfer belt. The pick-off pawls [9] also help separate the paper
from the drum.
ID SENSOR PATTERN WRITING/DETECTION
The laser projects a sensor pattern on the drum surface. The ID sensor [10]
measures the reflectivity of this pattern. The output signal from this measurement is
one of the factors used for toner supply control.
DRUM CLEANING
The cleaning brush [11] removes toner remaining on the drum after image transfer.
The cleaning blade and a retractable 2nd clean toner from the surface of the drum.
QUENCHING
The light from the quenching lamp [12] electrically neutralizes the charge on the
drum surface.
B234/B235/B236/D101/D102/D103 6-4 SM